Acrylonitrile polymer composition comprising a six membered heterocyclic n-substituted aldehyde and an inorganic acid and process of making same



2,878,220 Patented Mar. 11, was

YIDNITRILE POLYMER COMPOSITION COM- PRISING A SIX MEMBERED HETEROCYCLICNQUISTI'I'UTED ALDEHYDE AND AN INOR- GANIC ACID AND PROCW OF MAKING SAMEltichasdkllolmmlethesdmhld anduoyd'ldenkins,

Decatur signers ChemlranrlCorpora- ,Alm, toThe flan, Decatur, Ala, aeorpnratloaofDelaware NoDr-a ApplleatlonMay23,l95

2. CIli-III- (Cl. 280-32.)

The term polymer, as employed in the instant de scription and claims, isintended to include homopolymers, copolymers, and blends thereof, saidpolymers coirtaining at least 80 percent by weight of polymerized orcopolymerized acrylonitrile in the polymer molecule.

-Acrylonitrile polymers containing 80 percent or more of acrylonitrileare generally insoluble in the more common solvents. In those instanceswhere suitable solvents have been found, in order to efiect solution,the application of heat is usually necessary. Where heat is employed toetfect solutions, from which shaped articles are to be formed, a tan todark brown color frequently develops in the solutions and therefore iscarried over into the product formed therefrom. This color also developsin solutions upon standing for prolonged periods of time.

The mechanism which causes color formation has not been definitelyascertained, although a variety of reasons therefor have been advanced.The presence of metal ions, such as iron, copper and manganese in thesolutions may cause the color. The employment of amide compounds assolvents may result in formation of amines when heat is applied andcause color in the compositions. Impurities present in the solvents havealso been cited as a cause. Whatever may be the reason for colorformation, it results in compositions and products of undesirablestandards and therefore, has been the source of concern, particularly incommercial operations where such types of polymers or copolymers areemployed.

Accordingly, it is an object of the present invention to preventundesirable color formation in acrylonitrile polymer compositions.

Another obiect is to color formation when solutions of the acrylonitrilepolymers arepermitted to stand for a prolonged period of time or uponapplication of heat.

It is also an object of the invention to prevent color formation inacrylonitrile polymers at elevated temperatures.

A still further object of the invention is the production of solutionsof acrylonitrile polymers and articles produced therefrom havingimproved color characteristics.

Other objects and advantages will be apparent from a consideration ofthe description of the invention which follows hereafter.

In general, the objects of the invention are accomplished by dissolvingthe polymer of acrylonitrile in a suitable solvent therefor andpreventing or minimizing color formation by the presence in the solutionas an p 2 inhibiting agent, a combined reagent comprising a heterocyclicring compound having the general formula (I) CHr-CHs B CKr-cs where R is-&Ks or oxygen; and an inorganic acid having an ionization constantgreater than 1xl0- The components of the inhibiting agent may beemployed in equal or unequal amounts, any one constituentbeingpresentinarangeof99to1percentinatwocomponent system. The totalamount of inhibiting agent may be employed in a range of about 0.3 to 15percent, based on the total polymer weight. However, it is preferredthat the inhibiting agent of the instant invention be present in a smallamount compared to the amount of polymer dissolved. Thus, although theamount is not critical, it is preferred that the inhibiting agent bepresent intheamountofabout0.3to3percent,basedonthe total weight of thepolymer. The inhibiting agent may be added to the solvents before orafter the polymer is dissolved therein. The inhibiting agent permitsexposure to high temperatures for prolonged standing periods without thedevelopment of the objectionable color which usually results in suchsolutions. The compositions of the instant invention may be prepared ina varying temperature range. For example, the compositions of theinstant invention may be prepared by mixing the polymer, a suitablesolvent and the inhibiting agent at any temperature or heating themixture to a temperature up to the boiling point of the solvent.

Among the compounds bearing the general formula (I) which may beemployed in practicing the instant invention are N-formyl morpholine,N-formyl piperidine, etc. Among the acids having an ionization constantgreater than 1x10 which may be employed in practicing the instantinvention are sulfuric acid, nitric acid, phosphoric acid, hydrochloricacid, etc.

Among the solvents which may he used in practicing the instant inventionare N,N-dimethylformamide, N,N- dimethylacetamide, aqueous zincchloride, sulfuric acid, aqueous nitric acid, aqueous sodiumthiocyanatc, ethylene carbonate, sulfolane, nitromethane, etc.

The polymeric materials, which are employed in the practice of thepresent invention, are polyacrylonitrile, copolymers, including binaryand ternary polymers containing at least percent by weight ofacrylonitrile in the polymer molecule, or a blend comprisingpolyacrylonitrile or copolymers comprising acrylonitrile with from 2 to50 percent of another polymeric material, the blend having an overallpolymerized acrylonitrile content of at least 80 percent by weight.While the preferred polymers employed in the instant invention are thosecontaining at least 80 percent of acrylonitrile, generally recognized asthe fiber-forming acrylonitrile polymers, it will be understood that theinvention is likewise applicable to polymers containing less than 80percent acrylonitrile and the same stability is realized with theinhibiting agents defined herein. The acrylonitrile polymers containingless than 80 percent acrylonitrile are useful in forming films, coatingcompositions, molding operations, lacquers, etc., in all of whichapplications the alleviation of undesirable color is extremelyimportant.

For example, the polymer may be a copolymer of from 80 to 99 percentacrylonitrile and from 2 to 20 percent of another monomer containing theC= linkage and copolymerizable with acrylonitrile. Suitable monoolefinicmonomers include acrylic, alpha-chloroacrylic and mcthacrylic acids; theacrylates, such as methylmethacrylate, ethylmethacrylate,butylmethacrylate, methoxymethyl methacrylate, beta-chloroethylmethacrylate, and the corresponding esters of acrylic andalpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinylbromide, vinylidene chloride, l-chloro-l-bromoethylene;methacrylonitrile; acrylamide and methacrylamide;alpha-chloroacrylamide, or monoalky] substitution products thereof;methyl vinyl ltetone; vinyl carboxylates, such as vinyl acetate, vinylchloroacetate, vinyl propionate, and vinyl stearate, N-vinylimides, suchas N-vinylphthalimide and N-vinylsuccinimide; methylene malonic esters;itaconic acid and itaconic ester; N-vinylcarbazole; vinyl furane; alkylvinyl esters; vinyl sulfonic acid; ethylene alpha, beta-dicarboxylicacids or their anhydrides or derivatives, such as diethylcitraconate,diethylmesaconate, styrene, vinyl naphthalene; vinyl-substitutedtertiary heterocyclic amines, such as the vinylpyridines andalkylsubstituted vinylpyridines, for example, 2-vinylpyridine,4-vinylpyridine, Z-methyl-S-vinylpyridine, ctc.; l-vinylimidazole andalkyl-substituted l-vinylimidazoles, such as 2-, 4-, orS-methyl-l-vinylimidazole, and other C=C containing polymerizablematerials.

The polymer may be a ternary interpolymer, for example, productsobtained by the interpolymerization of acrylonitrile and two or more ofany of the monomers, other than acrylonitrile, enumerated above. Morespecifically, and preferably, the ternary polymer comprisesacrylonitrile, methacrylonitrile, and z-vinylpyridine. The ternarypolymers preferably contain from 80 to 97 percent of acrylonitrile, from1 to percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18percent of another substance, such as methacrylonitrile or vinylchloride.

The polymer may also be a blend of polyacrylonitrile or of a binaryinterpolymer of from 80 to 98 percent acrylonitrile and from 1 to 20percent of at least one other C=C containing substance with from 2 to 50percent of the weight of the blend of a copolymer of from 10 to 70percent of acrylouitrile and from 30 to 90 percent of at least one otherC=C containing polymerizable monomer. Preferably, when the polymericmaterial comprises a blend, it will be a blend of a copolymer of 90 to98 percent acrylonitrile and from 2 to 10 percent of anothermono-olettnic monomer, such as vinyl acetate, which is not receptive todyestutf, with a suflicient amount of a copolymer of from 10 to 70percent of acrylonitrile and from 30 to 90 percent of avinyl-substituted tertiary heterocyclic amine, such as vinylpyridine orI-vinylimidazole, to give a dyeable blend having an overallvinyl-substituted tertiary heterocyclic amine content of from 2 to 10percent, based on the weight of the blend.

The polymers, useful in the practice of the present invention, may beprepared by any conventional polymerization procedures, such as masspolymerization methods, solution polymerization methods, or aqueousemulsion procedures. However, the preferred practice utilizes suspensionpolymerization wherein the polymer is prepared in finely divided formfor immediate use in the fiber fabrication operations. The preferredsuspension polymerization may utilize batch procedures, wherein monomersare charged with an aqueous medium containing the necessary catalyst anddispersing agents. A more desirable method involves the semi-continuousprocedure in which the polymerization reactor containing the aqueousmedium is charged with the desired monomers and the continuouswithdrawal of polymer may also be employed.

The polymerization is catalyzed by means of any watersoluble peroxycompound, for example, the potassium, and other water-soluble salts ofperoxy acids, sodium peroxide, hydrogen peroxide, sodium perborate, thesodium salts of other peroxy acids, and any other water-soluble compoundcontaining a peroxy group (-0-O). A wide variation in the quantity ofperoxy compound is possible. For example, from 0.1 to 3.0 percent byweight of the polymerizable monomer may be used. The catalyst may becharged at the outset of the reaction, or it may be added continuouslyor in increments throughout the reaction for the purpose of maintainiuga more uniform concentration of catalyst in the reaction mass. Thelatter method is preferred because it tends to make the resultantpolymer more uniform in its chemical and physical properties.

Although the uniform distribution of the reactants throughout thereaction mass can be achieved by vigorous agitation, it is generallydesirable to promote the uniform distribution of reagents by using inertwetting agents, or emulsion stabilizers. Suitable reagents for thispurpose are the water-soluble salts of fatty acids, such as sodiumoleate and potassium stearate, mixtures of water-soluble fatty acidsalts, such as common soaps prepared by the saponification of animal andvegetable oils, the amino soaps," such as salts of triethanolamine anddodecylmethylamine, salts of rosin acids and mixtures thereof, thewater-soluble salts of half esters of sulfuric acid and long chainaliphatic alcohols, sulfonated hydrocarbons, such as alkyl arylsulfonates, and any other of a wide variety of wetting agents, which arein general organic compounds containing both hydrophobic and hydrophilicradicals. The quantity of emulsifying agents will depend upon theparticular agents selected, the ratio of monomer to be used, and theconditions of polymerization. In general, however, from 0.01 to 1.0percent by weight of the monomers may be employed.

The emulsion polymcrizations are preferably conducted in glass orglass-lined vessels which are provided with a means for agitating thecontents. Generally, rotary stirring devices are the most effectivemeans of insuring the intimate contact of the reagents, but othermethods may be successfully employed, for example, by rocking ortumbling the reactors. The polymerization equipment generally used isconventional in the art and the adaptation of a particular type ofapparatus to the reaction contemplated is within the province of oneskilled in the art. The articles manufactured therefrom may be producedby well-known conventional methods, for example, the wet-spinning,dry-spinning and melt-spinning methods for producing fibers.

The following examples are illustrative rather than limitative and allparts, proportions and percentages are by weight unless otherwisespecified.

EXAMPLE I 7.5 grams of a polymer blend of 88 percent of a co polymercontaining 94 percent of acrylonitrile and 6 percent of vinyl acetateand 12 percent of a copolymer of 50 percent of acrylonitrile and 50percent of Z-methyl- S-vinyl pyridine were added to 45 milliliters ofN,N- dimethylacetamide containing approximately 0.05 gram of titaniumdioxide. The mixture was stirred and heated to 70 C. It was then quicklycooled to room temperature and the color measured. This sample was usedas a control. The purity is set forth below. Subsequently, like sampleswere prepared but with 0.150 gram of a color inhibitor containing 0.075gram each of N-formyl morpholine and sulfuric acid; N-formyl piperidineand sulfuric acid. The purity is set forth below.

EXAMPLE I! 7.5 grams of an acrylonitrile homopoiymer were added to 45milliliters of N,N-dimethylacetatnide containing ap proximately 0.05gram of titanium dioxide. The mixture was stirred and heated for 50minutes at 90' C. It was then quickly cooled to room temperature and thecolor measured. This sample was used as a control. The purity of thecontrol sample is set forth below. Subsequently, like samples wereprepared but with 0.150 grams of an inhibiting agent containing 0.075gram each of N- formyl morpholine and sulfuric acid; N-formyl piperidineand sulfuric acid. The purity is set forth below.

Table II lnhibltor Percentage Pnrtt Used 7 Control. l. 5 N-tormylltcrphollne and Bult'urtc Acld....... 8 I. I N-lermyl Plperldlne andSulfuric Acid l t. 2

The tests for color indicative of approaching whiteness used throughoutthe examples consist of measurements of purity as calculated from thetristimulus values determined on a General Electric Spectrophotometer bythe methods recommended by the Standard Observer and 00- N ordinateSystem of the International Commission on 11- luminaticn, as fully setforth in the Handbook-f Colorimetry published by The Technology Press,Massachusetts Institute of Technology in 1936.

The compositions of the instant invention present many advantages. Forexample, products formed from the polymer solutions of the instantinvention are free of objectionable color and therefore of greatercommercial value. In preparing the polymer solutions, heat may beapplied without the danger of color formation and the solutions, ifnecessary, may stand for prolonged periods and remain free of color. Theinhibiting agents are readily available and inexpensive. Therefore, nogreat We claim:

1. A new composition of matter comprising a polymer containing at least80% of acrylonitrile and up to percent of another polymerizablemono-olefinic monomer therewith, a solvent therefor, and an inhibitingagent containing substantially equal proportions by weight of a compoundhaving the general formula OKs-OH: H B N-l=O OKs-U s wherein R isselected from the group consisting of CH,

and oxygen; and an inorganic acid having an ionization constant greaterthan 1x101 2. A new composition of matter as defined in claim 1 whereinthe polymer is a blend of 80 to 99 percent of (A) a copolymer containing90 to 98 percent of acrylonitrile and 2 to 10 percent of vinyl acetateand t to 20 peroentof (B) a copolymer containing 10 to 70 percent ofacrylonitrile and to 90 percent of Z-methyl-S-vinyl Py i 3. A newcomposition of matter as defined in claim 1 wherein the polymer ispoiyacrylonitrlle.

4. A new composition of matter as defined in claim 1 wherein theinhibiting agent contains N-formyl morpholine and sulfuric acid...

5. A new composition of matter as defined in claim I wherein theinhibiting agent contains N-formyl piperidine and sulfuric acid.

6. A new composition of matter as defined in claim 1 wherein the solventis N,N-dimethylacetamide.

7. A new composition of matter as defined in claim 1 wherein the polymeris a copolymer containing from 80 to 98 percent of acrylonitrile andfrom 2 to 20 percent of another polymerizable mono-olefinic monomercopolymerizable therewith.

8. A new composition of matter comprising a copolymer containing '80 to98 percent of acrylonitrile and 2 to 20 percent of vinyl acetate, asolvent therefor, and 0.3 to 15 percent, based on the total weight ofthe polymer, of an inhibiting agent, said inhibiting agent containingsubstantially equal proportions by weight of a compound having thegeneral formula,

carom a =0 wherein R is selected from the group consisting of -CH, andoxyg n. and sulfuric acid.

9. A new composition of matter comprising a polymer blend of (A) acopolymer containing 90 to 98 percent of acrylonitrile and 2 to 10percent of another polymerizable mono-olefinic monomer and (B) acopolymer containing 10 to 70 percent of acrylonitrile and 30 to 90percent of a vinyl substituted tertiary heterocyclic amine, said blendhaving an'overall vinyl substituted tertiary heterocyclic amine contentof from 2 to 10 percent based on the weight of the blend, a solventtherefor, and an inhibiting agent containing substantially equalproportions by weight of a compound having the general formula,

OKs-05s H CHr-C I wherein R is selected from the group consisting of CH,

- and oxygen; and aninorganic acid having an ionization constant greaterthan i X 10-.

10. A new composition of matter comprising a polymer blend of 80 to 99percent of (A) a copolymer containing to 98 percent of acrylonitrile and2 to 10 percent of vinyl acetate and 1 to 20 percent of (B) a copolymercontaining 10 to 70 percent of acrylonitriie and 30 to 90 percent of2-methyi-5-vinyl pyridine, a solvent therefor, and 0.3 to 1.5 percent,based on the total weight of the polymer, of an inhibiting agent, saidinhibiting agent containing substantially equal proportions by weight ofa compound having the general formula,

OKs-CH1- B OKs-01! n I wherein R is selected from the group consistingof -CH; and oxygen; and sulfuric acid.

12. A new composition of matter comprising polyacrylonitrile, a solventtherefor, and 0.3 to 15 percent, based on the total weight of thepolymer, of an inhibiting agent, said inhibiting agent substantiallyequal proportions by weight of a compound having the general formula,

wherein R is selected from the group consisting of --CH, and oxygen; andan inorganic acid having an ionization constant greater than lxl-'; andheating the mixture to form a homogeneous solution.

14. A method as defined in claim 13 wherein the polymer is a copolymercontaining from 80 to 98 percent of aeryionitn'le and from 2 to 20percent of another polymerizahle mono-olefinic monomer copolymerizabletherewith.

15. The method as defined in claim 13 wherein the polymer is a blend of80 to 99 percent of (A) a copolymer containing 90 to 98 percent ofacrylonitrile and 2 to 10 percent of vinyl acetate and l to 20 percentof (B) a copolymer containing 10 to percent of aerylonitrile and 30 to90 percent of Z-methyl-S-vinyl pyridine.

16. The method as defined in claim 13 wherein the polymer ispolyacrylonitrile.

17. The method as defined in claim 13 wherein the inhibiting agentcontains N-tormyl morpholine and suliuric acid.

18. The method as defined in claim 13 wherein the inhibiting agentcontains N-torm'yl piperidine and sulturic acid. a

19. The method as defined in claim 13 wherein the solvent isN,N-dimethylacetamide.

20. A method for preparing a new composition of matter comprising mixinga polymer blend of to 99 percent of (A) a copolymer containing to 98percent of acrylonitrile and ,2 to 10 percent of vinyl acetate and 1 to20 percent of (i!) a copolymer containing 10 to 70 percent ofacrylonitrile and 30 to 90 percent of Z-rnethyl- S-vinyl pyridine, asolvent therefor, and 0.3 to 15 percent, based on the total weight ofthe polymer, of an inhibiting agent, said inhibiting agent containingsubstantially equal proportions by weight of a compound having thegeneral formula,

OKs-CHI wherein R is selected from the group consisting of CH, andoxygen; and sulfuric acid, and heating 'the mixture to a temperature ina range of 25' C. to the boiling point of said mixture to form ahomogeneous solution.

References Cited in the file of this patent UNITED STATES PATENTS2,502,030 Scheiderbauer Mar. 28, 1950 UNITED STATES PATENT OFFICECertificate of Correction Patent No. 2,878,220 March 17, 1959 Richard R.Holmes et a1.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 2, line 69, for 99 read -98-; line 70, for C= read C=C column 3,line 30, for 97 read 98; line 36, for 98 read 99; column 5, line 55,claim 1, after monomer insert copolymerizable-; column 6, lines 64 and65, claim 11, after monomer insert copolymerizable; column 7, line 16,claim 13, after monomer insert copolymerizable-.

Signed and sealed this 1st day of September 1959.

Attea:

KARL H. AXLINE, ROBERT C. WATSON, Attesting Ofi'icer. Uom/miem'omr ofPatents.

1. A NEW COMPOSITION OF MATTER COMPRISING A POLYMER CONTAINING AT LEAST80% OF ACRYLONITRILE AND UP TO 20 PERCENT OF ANOTHER POLYMERIZABLEMONO-OLEFINIC MONOMER THEREWITH, A SOLVENT THEREFOR, AND AN INHIBITINGAGENT CONTAINING SUBSTANTIALLY EQUAL PROPORTIONS BY WEIGHT OF A COMPOUNDHAVING THE GENERAL FORMULA